1. Field of the Invention
The present invention relates to a disk device and an apparatus for writing a reference signal into the disk device or, in particular, to a housing structure of a disk device and an apparatus for writing a reference signal into the disk device, in which the unnecessary base vibration is reduced by improving the base rigidity to thereby realize a very close track pitch in the disk device.
2. Description of the Related Art
In recent years, disk devices such as magnetic disk devices and optical disk devices have found applications as an external storage units of computers. Signals are transmitted and received at ever-increasing speeds between the head and the control circuit of these disk devices and the storage capacity of the disk devices is increased every year. Once the disk size is fixed, the storage capacity is improved by increasing the TPI (tracks per inch) and hence reducing the pitch of the tracks on the disk.
With the increased density of the tracks due to an increased TPI, a slight vibration may displace the head from an intended track to deteriorate the reliability of the disk device. A disk device having a disk built therein having high-density tracks, therefore, is desirably improved in base rigidity to reduce vibration.
A conventional magnetic disk device which is a kind of a disk device generally comprises a bath-tub type of base housing therein at least a disk, a spindle motor for rotating the disk, a carriage with a head at the forward end thereof and an actuator having a voice coil motor. This base is enclosed by a cover through a gasket. In this magnetic disk device, the signal reproduced by the head is withdrawn out of the actuator by a flexible circuit board mounted on the side of the carriage and led to and demodulated by a circuit on a fixed board protruded from the bottom of the base.
The magnetic disk device requires work called a servo track write operation for writing the servo information as a reference signal into the disk at the time of manufacture thereof. This servo track write operation is performed with all the parts built into the magnetic disk device. At the time of servo track write operation, first, a reference head is inserted into the base from outside of the magnetic disk device, and a reference signal is written on the outermost peripheral portion of the disk on which nothing has been written. The outermost peripheral portion of the disk in which the reference signal is written is where nothing can be read from by the built-in head. Then, the reference signal thus written is reproduced by the reference head thereby to confirm the disk position, and the internal head is driven by an external source in accordance with the detected position thereby to write the servo information in the disk.
Generally, the disk in which the reference signal is written is located close to the base bottom. For this reason, a reference head insertion hole from which to insert the reference head is formed in the side of the base. Upon completion of the servo track write operation, the reference head is withdrawn out of the reference head insertion hole, which is then hermetically enclosed by attaching a seal over it.
In the conventional disk device, the base is vibrated by the rotation of the spindle motor at the time of servo track write operation, thereby deteriorating the quality of the servo signal written under that condition. There has not been available any means capable of writing the reference signal while suppressing the vibration of the disk device.
Further, in the case where the actuator of the conventional magnetic disk device is placed on a predetermined track while the device is in use, the vibration generated by the rotation of the spindle motor is transmitted to the base through the mounting end thereof thereby causes vibration of the base, or the base is vibrated due to the fact that the base bottom is flat, with the result that it becomes difficult for the actuator to remain stationary. In the worst case, the data cannot be read.
Furthermore, consider the conventional seek operation in which the actuator moves to a predetermined track of the disk while the disk device is in operation. The base is easily affected by the reaction force of the seek operation, so that the base is vibrated, thereby increasing the time required for moving to the predetermined track.
A higher density of track pitch is essential for the future realization of a high-capacity disk device. Nevertheless, the above-mentioned vibration problem makes it difficult to increase the density of the track pitch.
In view of this, a first object of the invention is to provide a housing structure of a disk device comprising a spindle motor with at least a recording disk mounted thereon, a carriage with at least a head mounted thereon for exchanging signals with the disk, an actuator for driving the carriage and a base of a bath-tub type having built therein the spindle motor, the carriage and the actuator, wherein the vibration of the base is reduced by improving the base rigidity, thereby making it possible to increase the density of track pitch.
A second object of the invention is to provide a housing structure having a reference head insertion hole for a disk device comprising a spindle motor with at least a recording disk mounted thereon, a carriage with at least a head mounted thereon for exchanging signals with the disk, an actuator for driving the carriage and a base of a bath-tub type having built therein the spindle motor, the carriage and the actuator, the disk device having such a configuration as to improve the rigidity of the base, wherein a reference signal can be written accurately in the disk at the time of manufacture of the disk device and the disk device is not adversely affected by the reference head insertion hole after writing the reference signal.
A third object of the invention is to provide an apparatus for writing a reference signal into a disk device having a housing structure for achieving the above-mentioned first and second objects.
In order to achieve the above-mentioned first object, according to the present invention, there is provided a housing structure of a disk device comprising a spindle motor with at least a recording disk mounted thereon, a carriage with at least a head mounted thereon for writing information into or reading information from the disk, an actuator for driving the carriage and a base of a bath-tub type having built therein the spindle motor, the carriage and the actuator, wherein the spindle motor, the carriage and the actuator are hermetically sealed by a cover mounted on the upper surface of the base, and the base includes a reference head insertion hole into which a reference head is inserted for writing the reference signal into the disk at the time of manufacture of the disk device, the housing structure further comprising at least a damping means mounted on the bottom of the base of a bath-tub type or on the base side adjacent to the bottom for reducing the vibration of the base.
In the first form of the damping means, the thickness of the base bottom plate is increased to a maximum within a specified base size. In the case where the disk device is of a 3.5-in. type, for example, the thickness of the base bottom plate can be increased to 5 mm or more.
According to the first form of the damping means, the increased thickness of the base bottom plate increases the base rigidity and thereby reduces the base vibration.
In a second form of the damping means, the hole for mounting the spindle motor formed in the base is reduced in size, a protrusion is formed on the base for accommodating the flange of the spindle motor, and a mounting hole of the required minimum size is formed at the forward end surface of the protrusion. In the case where the disk device is of 3.5 inch type, for example, the size of the mounting hole can be defined as 13.5 mm or less.
According to the second form of the damping means, the size of the mounting hole for the spindle motor formed in the base is so small that the base rigidity is higher than when the mounting hole is large, thus reducing the base vibrations.
In a third form of the damping means, at least a rib is formed on the base bottom. This rib is formed in such a manner as to connect at least the outer peripheral portion of the base protrusion in the second form of the damping means to at least a vibration source on the base. The base vibration source includes the longitudinal ends of the base, a threaded hole of the central shaft of the head actuator, at least a threaded hole for mounting the printed board or at least a threaded hole used for incorporating the disk device in an external device.
According to the third form of the damping means, at least a rib is arranged in such a position as to connect to at least a vibration source on the base bottom, and therefore the base rigidity is increased and the base vibrations reduced.
In a fourth form of the damping means, a pair of walls are protruded continuously from and along the two longitudinal edges of the base.
According to the fourth form of the damping means, the walls protruded continuously along the longitudinal edges of the base increase the base rigidity for a reduced base vibration.
In a fifth form of the damping means, a reference head insertion hole into which to insert a reference head is formed in the portion of the base bottom surface corresponding to the outer peripheral portion of the disk. This reference head insertion hole can alternatively be located in the neighborhood of one of the continuous walls, if any, along the longitudinal edges of the base as in the fourth form of the damping means.
According to the fifth form of the damping means, the reference head insertion hole is located in the base bottom base, and therefore the sides of the base can be reinforced to reduce the base vibrations.
In a sixth form of the damping means, first, second and third reference surfaces are formed in the neighborhood of different sides of the base bottom for fixing the disk device firmly to a reference signal writing jig in vertical direction at the time of writing a reference signal in the disk in the process of manufacture of the disk device. These first to third reference surfaces are arranged in positions in contact with the reference points formed on the jig, respectively. When fixing the disk device to the jig in vertical direction using the first to third reference surfaces, therefore, the portions of the base in vertically opposed relation to the reference surfaces can be held, and a base component member is filled between the reference surfaces and the base portions thus held. One of the first to third reference surfaces is arranged on a line dividing the line connecting the other two reference surfaces into two equal portions.
According to the sixth form of the damping means, the profile of the cover mounted on the upper surface of the base is reduced in size as compared with the base profile by more than the thickness of the base, so that the cover mounted on the mounting portion of the internal peripheral surface of the base is not protruded above the upper surface of the base. Thus, the disk device can be fixed on the jig with the cover attached thereto.
In a seventh form of the damping means, fourth, fifth and sixth reference surfaces are further added to the sixth form of the damping means for fixing the disk device firmly to the reference signal writing jig in horizontal direction in the neighborhood of a pair of adjacent sides of the base. These fourth to sixth reference surfaces are arranged in contact with the corresponding reference points respectively formed on the jig. When fixing the disk device to the jig in horizontal direction using the fourth to sixth reference surfaces, the side portions of the base in vertically opposed relationships to the reference surfaces can be held, and a base component member is filled between the reference surfaces and the side portions thus held.
According to the sixth form of the damping means, the first, second and third reference surfaces are arranged in the neighborhood of different sides, respectively, of the base bottom in such a manner as to contact the corresponding reference points on the jig for writing the reference signal in the disk device. According to the seventh form of the damping means, on the other hand, the fourth, fifth and sixth reference surfaces are formed in the neighborhood of adjacent sides of the base. When fixing the disk device to the jig at the time of manufacturing the disk device, therefore, the base is firmly fixed on the jig thereby to reduce the base vibrations.
Further, if a depression is formed on the upper surface of the cover mounted on the upper surface of the base and a damping plate is mounted in the depression, then the vibrations are reduced further.
The second object of the invention can be achieved by providing the reference head insertion hole in any of the forms described below.
In a first form of the reference head insertion hole, the reference head insertion hole is formed in the outermost peripheral portion of the disk downstream in the direction of disk rotation with respect to the position of the read/write head of the disk device.
In a second form of the reference head insertion hole, the reference head insertion hole is formed in the innermost peripheral portion of the disk downstream in the direction of disk rotation with respect to the position of the read/write head of the disk device.
In a third form of the reference head insertion hole, the reference head insertion hole is formed at least a predetermined distance away from the position of a circulation filter mounted on the base.
In a fourth form of the reference head insertion hole, the reference head insertion hole is formed on the same side as a connector of the read/write cable adapted to be withdrawn from the base.
In a fifth form of the reference head insertion hole, the reference head insertion hole is enclosed with a seal member after a reference signal is written in the disk.
In a sixth form of the reference head insertion hole, the seal member for the fifth form of the reference head insertion hole is made of a material capable of shielding an electromagnetic wave generated by an external source.
In a seventh form of the reference head insertion hole, the seal member is used also as a material for filling the space in the reference head insertion hole thereby to form a smooth and continuous boundary between the inner surface of the base and the reference head insertion hole.
According to the first to fourth forms of the reference head insertion hole of the present invention, a reference signal can be accurately written in the disk at the time of manufacture of the disk device. Also, according to the fifth to seventh forms of the reference head insertion hole of the invention, the disk device is not adversely affected by the reference head insertion hole after the reference signal is written.
An apparatus for writing a reference signal in the disk device according to the present invention, on the other hand, is for writing a reference signal into the disk device using a reference head, the disk device including a spindle motor with at least one recording disk mounted thereon, a carriage with at least one head mounted thereon for writing information into the disk or reading information from the disk, an actuator for driving the carriage, a base of a bath-tub type for accommodating the spindle motor, the carriage and the actuator therein, and a cover mounted on the upper surface of the base for hermetically sealing the spindle motor, the carriage and the actuator, wherein the base includes a reference head insertion hole by way of which the reference head is inserted for writing the reference signal into the disk at the time of manufacture of the disk device. The apparatus is fabricated in any of the forms described below.
A first form of the reference signal writing apparatus comprises a plurality of reference rests in contact with first, second and third reference surfaces, respectively, arranged in the neighborhood of different sides of the bottom of the base and having the top surfaces thereof in the same plane for fixing the base in vertical direction, a plurality of reference protrusions arranged in contact with fourth, fifth and sixth reference surfaces, respectively, formed on a pair of adjacent sides of the base for fixing the base in horizontal direction, a first holding member for pressing the first, second and third reference surfaces of the base against the reference rests, and a second holding member for pressing the fourth, fifth and sixth reference surfaces of the base against the reference protrusions.
According to the first form of the reference signal writing apparatus, the base of the disk device is firmly fixed at the time of writing the reference signal, and therefore the reference signal can be written with a high reliability.
In a second form of the reference signal writing apparatus, the reference head is an in-line type in which a head slider including a write head and an arm for holding the head slider are substantially aligned with each other.
According to the second form of the reference signal writing apparatus, the reference head can be used also as the read/head write head of the magnetic disk device.
A third form of the reference signal writing apparatus comprises a moving mechanism called a pin-pick-mechanism for moving the head actuator in the disk device with a pin and a laser displacement meter for detecting the position of the pin pick mechanism, wherein the pin pick mechanism includes a mirror for reflecting the laser light emitted from the laser displacement meter, and the reference head is arranged on the same side as the mirror.
According to the third form of the reference signal writing apparatus, the reference head is located on the same side as the pin pick mechanism, and therefore the reference head and the pin pick mechanism can be driven on the same side, thereby reducing the size of the mechanism of the reference signal writing apparatus.
In a fourth form of the reference signal writing apparatus, the reference head is loaded in or unloaded from the disk device by a holding mechanism which operates to move the reference head toward or away from the disk surface in substantially the vertical direction.
According to the fourth form of the reference signal writing apparatus, the reference head insertion hole can be formed in the base bottom of the disk device.
In a fifth form of the reference signal writing apparatus, the reference head is mounted replaceably on the holding mechanism.
According to the fifth form of the reference signal writing apparatus, the reference head can be easily replaced when worn out, and thus the operating efficiency of the reference signal writing apparatus can be improved.
A sixth form of the reference signal writing apparatus comprises a protective cover mounted on the apparatus body for protecting the reference head not in use.
According to the sixth form of the reference signal writing apparatus, the reference head can be protected while not in use.
In a seventh form of the reference signal writing apparatus, the protective cover is so constructed as to automatically open when the disk device is loaded in the reference signal writing apparatus.
According to the seventh form of the reference signal writing apparatus, the insertion of the reference head into the disk device can be automated while protecting the reference head.